Though there are variations in the quality of whey protein, there are good ones that are certainly very beneficial in my opinion. You do need a good quality protein supplement in and around workouts for best results-some say that a degree of supplementation is beneficial before, during and after the workout. I usually go with during and after. The fast acting proteins like whey isolate or the even faster acting whey hydrolysate (usually more expensive) are ideal for this.
Just as you say you’d like to see studies proving their effectiveness, I’d like to see studies proving quality supplementation to be ineffective. I think many have received positive results in their own experiences regardless of studies. Slow digesting proteins are just not as effective during or immediately after. The concept or practice of properly timing the use of supplementation with respect to the training session is also very important. I think you will find many with this same experience.
I’m not pushing a brand but simply stating that a supplement with a approx. 4:1 carb to protein ratio is often cited at a good choice. Though there are at times variation in the recommended ratio depending upon at what time you are in relation to the workout, a supplement can still be quite useful. For example, many hours after the workout, besides or even possibly in addition to consuming whole food sources (meals), it’s often recommended to have a smaller ratio of carbs to protein.